Unipolarized wave refractor



P 15, 1953 w. E. KOCK 2,652,493

UNIPQLARIZED WAVE REFRACTOR Original Filed May 16, 1947 2 Sheets-Sheet 1 FIG. I

FRONT VIEW OFLENS I30 uwe/vro WE. KOCK Br ATTORNEP Sept. 15, 1953 w. E. KOCK v UNIFOLARIZED WAVE REFRACTOR Original Filed May 15, 1947 2 Sheets-Sheet 2 il l) k r ll I I II I I/ I l n I I I I JNVENTOR W. E/(OCK ATTORNEY Patented Sept. 15, 1953 UNITED STATES PATENT QFFICE UNIPOLARIZED WAVE REFRACTOR Winston E. Kock, Basking Ridge, N. J., assignor to Bell Telephone Laboratories, Incorporated,

New York, N. Y., a corporation of New York (or. zed-sass) 11 Claims.

This invention relates to unipolarized wave refractors for changing the phase velocity of high frequency wave energy.

This application is a division of my copending application Serial No. 748,448, filed May 16, 1947 which matured as United States Patent 2,577,619 granted December a, 1951'. I

A principal object of the invention is to provide refractors for changing the phase velocity of high frequency wave energy which will have substantially increased effective indices of refraction.

Other and further objects will become apparent during the course of the following description of preferred illustrative embodiments of the invention and from the appended claims.

The principles of the invention will be more readily understood. in connection with the following detailed description of the illustrative embodiments illustrated in the accompanying drawings in which:

Fig. 1 shows a front view of one preferred specific embodiment of a structure of the invention;

Fig. 2 shows, in a partially expanded perspective view, the form of refractor of Fig. 1 together with associated transceiving means;

3 shows a front view of a second specific embodiment of a retracting structure of the invention;

Fig. t shows, in an expanded perspective view,

the individual component vertical arrays, in the direction of wave propagation, of grids or rods which, when assembled as shown in Fig. 3, form the second preferred form of refractor of the invention; and

Fig. 5 is a side view of a centrally positioned component vertical array of the device of Fig. shown together with appropriate transceiving means.

In more detail in Figs. 1 and 2, reference numeral l3?) denotes a unipolarized, circularly symmetrical, piano-convex, strip lens of simple lightweight construction. The lens I36 comprises six cellophane panel sheets I3], I33, I35, lt'i, 539 and t lt, and five solid dielectric, celloi-hane or polystyrene foam, spacer sheets i32,

I36, E38 and hit, a spacer sheet being positioned between adjacent panel sheets as shown. Each panel sheet contains a circular lens panel i612 comprising a plurality of conductive tin foil strips 3 fastened to the front surface of the panel sheet. The lens panels have graded diameters, and hence different pluralities of strips. The lengths and arrangement of the strips is such that the outermost surfaces of the outermost strips and the ends of all the strips lie in and define the contour of a predetermined conventional shape of wave refractor, such as, for the resent example, that of a piano-convex lens.

As in the grid prism of Fig. 10 of my abovementioned copending parent application, the correspondingstrips in adjacent panels are not aligned, but are staggered. Thus, the eight strips 3 of panel sheet i553 are staggered relative to the nine strips 3 of panel sheet iSi, and are therefore opposite the eight spaces 5' of panel sheet 35. Also, the lens axis 9? passes through the central strip 3 of panel sheet iZ-ii and the through M3 between the two central strips 3 on panel sheet The panel and spacer sheets are held together by means of the wooden ring the wooden ring hi5 and the bolt-and-nut assemblies t lt; and the lens is supported by the stand fill. As in the structures described in my above-mentioned copending parent application, the refractive index n is greater than unity for waves having the E -vector 2i and is dependent upon the values selected for the factors W and N, where W is the vertical width of each strip and N is the number of strips per unit area in a vertical cross-section of the lens taken through its center in the direction of propagation. The lens i 38 has, as indicated in Fig. 2, a point focus 98 and its convex face is toward the horn 99.

The operation of the system R39, 99, Fig. 2, is the same as that of the system iii, 99 of Fig. 11 of my above-mentioned copending parent application. Thus, for waves electrically polarized parallel to the strip width W, as indicated by vector 2 i, the lens focuses the waves in all planes containing the optical axis 97 and the system list), 99 of Fig. 2 has a point-beam characteristic.

Referringto Figs. 3, 4 and 5, reference'numeral i denotes a unipolarized, circularly symmetrical, piano-convex grid lens of simple lightweight construction. The lens $53 comprises an array sea of 'horizontal grid members each horizontal grid member comprising a plurality of vertical metallic rod elements 2 1. The rods 2? are spaced, along the X dimension of the lens, a distance Sn smaller than a half wavelength apart and have lengths corresponding to the desired grid width W. The grids 2d are arranged in seven circular vertical panels i552, i515, i5 3, i529, ltd, i5? and iiiii'extending parallel to the XY plane. The panels 952 to 1'58 have graded diameters, and the component rods 2? are disposed and arranged so that the outermost sur faces of the outermost rods lie in and define the contour of a predetermined conventional shape of wave refractor, such as, for the present example, that of a plano-convex lens.

Alternatively, the structure of Figs. 3, 4 and 5 can be considered as one in which the rod elements 26 are arranged in eleven plano-convex vertical curtains [59 to I69, extending parallel to the YZ plane. In the YZ plane the rod elements 26 of each curtain are staggered in the direction of wave propagation, as shown, so that rods of each vertical row are, horizontally, opposite spaces of the next adjacent row or rows.

The rods are arranged in a maximum number of fifteen horizontal tiers I10, as indicated in Figs. 3 to 5, inclusive. More specifically, panels 52, 153, I54, l55, I56, I51 and I58 have, respectively, eight, seven, six, seven, six, five and two tiers, the rods in adjacent tiers or in adjacent panels in the direction of wave propagation being staggered, as described above.

The rods 2? are mounted in vertical polystyrene foam slabs l1, one for each of curtains I59, to 159, as shown in the expanded perspective view of Fig. 4, and the slabs extend parallel to the YZ plane and are, of course, spaced the same horizontal distance Sx, apart, as are the rods.

The .Sy and S2 spacings of the grids 26 are each smaller than a wavelength and, as in the structures of Figs. 3 and 5 of my above-mentioned copending parent application, preferably less than a half wavelength.

The slabs I'll are held in position by tightly fitting slots in the single wooden ring I48.

As before, the refractive index n of the lens E55 is greater than unity for waves having the vertical E-vector 2i, and is dependent upon the values selected for W and N, where W is the vertical dimension of the grid arrays 26 and N is the number of arrays per unit area in a vertical cross-section of the lens taken through its center in the direction of ropagation. The lens 555 has a point focus 98 and is unipolarized; and its convex face is toward the horn 99.

The operation of a system such as is indicated by the showing of Fig. 5, comprising the lens I50 and the horn 99, is the same, for waves having the E-vector 2i, as that of the system 535, 99, Fig. 2. As regardsthe I-I-vector components, if any, these components pass through the grid lens 15!), Fig. 3, whereas they are reflected by the lens I30.

If desired, matching sections of tapered dielectric constant may be utilized on each face of the lenses we and 50) in order to minimize the refiection losses, if any.

The type of construction utilized in the strip lens E30, Fig. 1 and the grid lens I58, Fig. 3, permits a relatively very close spacing Sz (in the direction of propagation). By reason of the close spacing, and also by virtue of the staggered arrangement, a high effective dielectric constant, and therefore a high delay, are obtainable. w

The measured eifective dielectric constants of a strip array and a grid array, constructed in accordance with Figs. 1 and '3, respectively, were 225 and 20, respectively.

The strip type refractor, one form of which is illustrated by Figs. 1 and 2 and which in the form shown has a dielectric constant of 225, is

especially suitable for use in a traveling wave tube since the corresponding refractive index is 15. A tube filled with this type of refractive structure would have a phase velocity 2: of Do/ 15, that is, l/15 the velocity of the same waves if propagated in free space.

Staggering of the strips, orgrids, as. taught 7 ductive metal parallel to said first minor axis,

secutive strips or grids in the same XY plane layer of the lens. Also, obviously, other arrangements of staggering consecutive XY plane panels of strips or grids can readily be devised which will result in longer minimum wave energy paths and hence, larger effective refractive indices for the over-all assembly.

Numerous and varied other arrangements clearly within the spirit and scope of the invention will readily occur to those skilled in the art. The above-described arrangements are merely illustrative and by no means exhaustively cover the applications of the principles of the invention as disclosed.

What is claimed is:

1. A passive refractor for retarding linearly polarized electromagnetic waves within a predetermined range of frequencies and having predetermined directions of polarization and propagation, said refractor having a principal axis and a first and a second minor axes, each of said three axes being perpendicular to the other two, said refractor comprising a plurality of plane panels arranged along said principal axis, said panels being perpendicular to said principal axis and parallel to each other, each of said panels comprising a plurality of parallel portions, each of said portions having a substantially uniform width parallel to said first minor axis which is less than one-half wavelength of the highest frequency to be employed, a substantially uniform length parallel to said second minor axis which is large with respect to said width, and a substantially uniform thickness parallel to said principal axis which is small with respect to said width, alternate ones of said lurality of parallel portions of each said panel having substantially identical width dimensions and including sufficient electrically conductive metal in a solid state to totally reflect linearly polarized, electromagnetic waves within said frequency range having a direction of polarization parallel to said first minor axis, the portions intermediate said alternate portions'of said plurality of parallel portions of each said panel having substantially identical width dimensions and being of dielectric material substantially freely passing linearly polarized electromagnetic waves withinsaid frequency range having a direction of polarization parallel to said first minor axis,'adjacent successive panelsalong. said principal axis having the reflecting portions of one panel in alignment with thenon-reflecting portions of the other I termined direction of polarization.

2. The refractor of claim 1, in which said refleeting portions include continuous strips of electrically conductive metal in a solid state coextensive With said portions. 3. The'refractor of claim 1, in which said reflecting portions include wires of electrically conextending across the width of said portions and uniformly spaced, in the direction of said second minor axis, less than one-half wavelength apart of the highest frequency to be employed.

4, The refractor of claim 1, in which the spacing between each two successive adjacent panels in the direction of said principal axis is less than one-quarter wavelength of the highest frequency to be employed.

5. The refractor of claim 1, in which the outermost surfaces of the outermost portions of the metallic conducting elements lie in and define the contour of a simple optical refracting device.

6. The refractor of claim 5, in which the contour defined by the outermost surfaces of the outermost portions of the metallic conducting elements is that of a convex optical lens.

'7. The refractor of claim 5, in which the contour defined by the outermost surfaces of the outermost portions of the metallic conducting element is that of a plano-convex optical lens.

8. A passive refractor for retarding linearly polarized electromagnetic waves within a predetermined range of frequencies and having a predetermined directions of polarization and propagation, said refractor comprising a plurality of plane curtains, arranged parallel to each other along a common principal axis, each curtain comprising a plurality of parallel strips alternately of conductive material in a solid state and dielectric material, the widths of all said strips being substantially uniform and less than onehalf wavelength of the highest frequency to be employed, the lengths of said strips being substantially uniform and large with respect to their widths, the thickness of each conductive strip being small with respect to its width, the spac ing between consecutive curtains along said principal axis being slightly greater than the thickness of said conductive strips, the conduc tive strips of each curtain being aligned with the dielectric strips of the next preceding and succeeding curtain in the direction of said principal axis whereby the said refractor has a large index of refraction to linearly polarized electromagnetic waves within said band of frequencies having a direction of propagation parallel to said principal axis and a direction of polarization parallel to the width dimensions of said strips.

9. The refractor of claim 8, wherein each of said strips of conductive material are replaced by a grid of parallel wires extending across the width of the strip and spaced along said strip at intervals of less than one-half wavelength of the highest frequency to be transmitted.

10. The refractor of claim 9, in which the outermost surfaces of the outermost wires lie in and define the contour of a convex optical lens.

11. The refractor of claim 8, in which the outermost surfaces of the outermost conductive strips lie in and define the contour of a convex optical lens.

WINSTON E. KOCK.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,064,582 Wolff Dec. 15, 1936 2,288,735 OConnell July 7, 1942 OTHER REFERENCES Electronics, March 1946, page 101. 

